Planar heat pipe

ABSTRACT

The planar heat pipe includes a metallic tube composed of two flat extensions and a shrinked intermediate structure, a wick structure, a working fluid and a support element. The flat extensions are separately located at two ends of the metallic tube. The intermediate structure connects between the flat extensions. The wick structure is arranged in the metallic tube. The working fluid is injected in the metallic tube and attached in the wick structure. The support element is disposed in the metallic tube for supporting the wick structure.

BACKGROUND OF THE INVENTION

1. Technical Field

The invention generally relates to heat dissipation devices, particularly to heat pipes.

2. Related Art

Integrated circuits (ICs) are broadly applied in various industrial equipments, measurement instruments and computers. With the development of electronic industries, ICs work at higher and higher frequencies and then generate more and more heat. ICs tend to damage if overheating. Conventional heat dissipation devices simply employing fins are not enough to satisfy requirement of heat dissipation of modern ICs. Thus heat pipes become popular in heat dissipation devices. Conventional heat pipes are tubular in shape and composed of a metallic tube, a wick structure arranged in the tube and a working fluid injected in the tube. The heat pipes can rapidly transfer a large amount of heat by phase change of the working fluid.

However, modern electronic devices tend toward lighter, thinner, shorter and smaller than ever. Conventional heat pipes become hard to be applied in a limited space. On the other hand, a heat pipe connecting a heat source to a heat sink usually must make a turn to evade other components. This situation has the design of heat dissipation become difficult.

SUMMARY OF THE INVENTION

An object of the invention is to provide a planar heat pipe which can only occupy a flat space and easily evade other components for increasing the space utilization.

To accomplish the above object, the planar heat pipe of the invention includes:

a metallic tube composed of two flat extensions located at two ends thereof and a shrinked intermediate structure connecting between the flat extensions;

a wick structure arranged in the metallic tube;

a working fluid in the metallic tube; and

a support element in the metallic tube for supporting the wick structure to attach the metallic tube.

In above structure, the flat extensions can be separately attached to a heat source and a heat sink. The flat extensions can be accommodated in a very flat space. And the intermediate structure can be provided with a turn to evade other components.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the original shape of the metallic tube;

FIG. 2 shows the metallic tube which has been shrinked;

FIG. 3 shows the metallic tube which has been pressed into a flat shape;

FIG. 4 shows the metallic tube which has been provided with the wick structure;

FIG. 5 is a cross-section view of the metallic tube with the support element;

FIG. 6 shows the metallic tube which has been sealed;

FIG. 7 shows an application of the planar heat pipe associated with a heat source; and

FIG. 8 is a cross-section view of FIG. 7.

DETAILED DESCRIPTION OF THE INVENTION

The planar heat pipe of the invention includes a metallic tube 10 composed of two flat extensions 11, 12 and an intermediate structure 13, a wick structure 20, a working fluid 30 and a support element 40.

Please refer to FIG. 1. A circular metallic tube 10 is used to be an original material of a heat pipe. The metallic tube 10 is made of material with great thermo-conductivity such as, but not limited to, copper.

Please refer to FIGS. 2 and 3. The flat extensions 11, 12 are located at two ends of the metallic tube 10 and the intermediate structure 13 is located between the two flat extensions 11, 12.

The intermediate structure 13 is made by a shrink process. The shrink process can be preferably performed by the tube spinning. The intermediate structure 13 is elongated with maintaining a circular cross-section. The intermediate structure 13 still keeps hollow even if it has been elongated. Two tapering portions 111, 121 are formed between the intermediate structure 13 and the extensions 11, 12. The tapering portions 111, 121 taper from the extensions 11, 12 to the intermediate structure 13.

The intermediate structure 13 may be made with a turn to satisfy real requirements. The embodiment shown in the drawings is with a turn. As can be seen in FIG. 3, a turn 131 is formed in the intermediate structure 13. The metallic tube 10 is pressed to become flat, i.e. the extensions 11, 12, tapering portions 111, 121, intermediate structure 13 and turn 131 are deformed into a flat shape. This flat shape can make the heat pipe accommodated in a thin space.

Please refer to FIGS. 4-6. The wick structure 20 is disposed in the metallic tube 10 through an opening thereof. The wick structure 20 attaches an inner side of the metallic tube 10. A gas passage is remained in the metallic tube 10. The wick structure 20 is made of porous material such as sintered powder.

The working fluid 30 is injected in the metallic tube 10 through its opening. The working fluid is absorbed by the wick structure 20 due to the capillary force. The total volume of the injected working fluid 30 is equal to the total volume of all pores of the wick structure 20.

The support element 40 is disposed in the metallic tube 10 to prevent the metallic tube from caving. The support element 40 pushes the wick structure 20 to attach the inner side of the metallic tube 10.

The metallic tube 10 must be degassed before its opening is sealed because the gas inherently filled in the metallic tube 10, such as air, does not involve the phase change of the working fluid 30. A heat pipe can not work normally if the gas has not been degassed.

Please refer to FIGS. 7 and 8. Either of the flat extensions 11, 12 serves as an evaporating section for attaching a heat source 50. The evaporating section can attach the heat source 50 planarly and tightly due to its flat shape. The other one of the flat extensions 11, 12 serves as a condensing section for attaching a fin set 60. The intermediate structure 13 is smaller than the flat extensions 11, 12 so that it can easily pass through or evade other components.

The flat extensions 11, 12 can be easily accommodated in a limited space such as a laptop computer. On the other hand, the evaporating section may be further extended to attach more heat sources. So the manufacturing costs can be reduced.

Although the present invention has been described with reference to the foregoing preferred embodiment, it will be understood that the invention is not limited to the details thereof. Various equivalent variations and modifications can still occur to those skilled in this art in view of the teachings of the present invention. Thus, all such variations and equivalent modifications are also embraced within the scope of the invention as defined in the appended claims. 

What is claimed is:
 1. A planar heat pipe comprising: a metallic tube composed of two flat extensions located at two ends thereof and a shrinked intermediate structure connecting between the flat extensions; a wick structure arranged in the metallic tube; a working fluid in the metallic tube; and a support element in the metallic tube for supporting the wick structure to attach the metallic tube.
 2. The planar heat pipe of claim 1, wherein the metallic tube is made of copper.
 3. The planar heat pipe of claim 1, further comprising two tapering portions formed between the intermediate structure and the extensions.
 4. The planar heat pipe of claim 1, further comprising a turn formed in the intermediate structure.
 5. The planar heat pipe of claim 1, wherein the intermediate structure is flat in shape.
 6. The planar heat pipe of claim 1, wherein the wick structure is sintered powder. 